23 Oct 2026 15:48:27 UTC
pay-rails/pay: non-constant-time HMAC comparison in Paddle Billing webhook signature verifier
cve-program · CVE-2026-70658 · Published
CVE-2026-70658
pay-rails/pay: non-constant-time HMAC comparison in Paddle Billing webhook signature verifier
CVSS 3.1 7.4 HIGHCheck source for fixed versionsKEV status unknown
cve-program · CVE-2026-70658
PublishedPay is a payments engine for Ruby on Rails 6.0 and higher. Prior to 11.6.2, Pay::Webhooks::PaddleBillingController#valid_signature? in app/controllers/pay/webhooks/paddle_billing_controller.rb compares the computed 64-character SHA-256 HMAC with the attacker-controlled h1 token from the Paddle-Signature header using Ruby String#==. An unauthenticated remote attacker who can repeatedly submit requests to /pay/webhooks/paddle_billing and obtain sufficiently precise timing measurements can infer matching digest prefixes and recover a valid signature. A forged accepted webhook is enqueued through Pay::Webhooks::ProcessJob and can cause a host application to update billing state, provision paid features, record refunds, or trigger customer notifications. This issue is fixed in version 11.6.2.
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